2.2.3. Ex Vivo Pharmacokinetic (PK) Studies

Drug elution from the strings was investigated ex vivo in a porcine model. In these studies, fresh normal esophageal tissue explants of pigs were used (Supplementary Figure S2A). These studies were performed on FTS coated strings with dimensions of 20 mm height and 2 mm cross-sectional diameter. Strings were inserted into approximately 20 mm of esophageal tissue section and incubated in 10 mL of PBS (to simulate the in vitro environment under sink conditions) at 4 °C for various durations (1 day and 3 days). A temperature of 4 °C was chosen for the study in order to preserve the fresh esophageal tissue. At each respective timepoint, the strings were removed, and the entire esophageal tissue was collected for PK analysis by LC-MS/MS analysis. In addition, residual FTS in the strings was extracted using acetonitrile and quantified by HPLC analysis.